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shared.xs
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shared.xs
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/* shared.xs
*
* Copyright (c) 2001-2002, 2006 Larry Wall
*
* You may distribute under the terms of either the GNU General Public
* License or the Artistic License, as specified in the README file.
*
* "Hand any two wizards a piece of rope and they would instinctively pull in
* opposite directions."
* --Sourcery
*
* Contributed by Artur Bergman <sky AT crucially DOT net>
* Pulled in the (an)other direction by Nick Ing-Simmons
* <nick AT ing-simmons DOT net>
* CPAN version produced by Jerry D. Hedden <jdhedden AT cpan DOT org>
*/
/*
* Shared variables are implemented by a scheme similar to tieing.
* Each thread has a proxy SV with attached magic -- "private SVs" --
* which all point to a single SV in a separate shared interpreter
* (PL_sharedsv_space) -- "shared SVs".
*
* The shared SV holds the variable's true values, and its state is
* copied between the shared and private SVs with the usual
* mg_get()/mg_set() arrangement.
*
* Aggregates (AVs and HVs) are implemented using tie magic, except that
* the vtable used is one defined in this file rather than the standard one.
* This means that where a tie function like FETCH is normally invoked by
* the tie magic's mg_get() function, we completely bypass the calling of a
* perl-level function, and directly call C-level code to handle it. On
* the other hand, calls to functions like PUSH are done directly by code
* in av.c, etc., which we can't bypass. So the best we can do is to provide
* XS versions of these functions. We also have to attach a tie object,
* blessed into the class threads::shared::tie, to keep the method-calling
* code happy.
*
* Access to aggregate elements is done the usual tied way by returning a
* proxy PVLV element with attached element magic.
*
* Pointers to the shared SV are squirrelled away in the mg->mg_ptr field
* of magic (with mg_len == 0), and in the IV2PTR(SvIV(sv)) field of tied
* object SVs. These pointers have to be hidden like this because they
* cross interpreter boundaries, and we don't want sv_clear() and friends
* following them.
*
* The three basic shared types look like the following:
*
* -----------------
*
* Shared scalar (my $s : shared):
*
* SV = PVMG(0x7ba238) at 0x7387a8
* FLAGS = (PADMY,GMG,SMG)
* MAGIC = 0x824d88
* MG_TYPE = PERL_MAGIC_shared_scalar(n)
* MG_PTR = 0x810358 <<<< pointer to the shared SV
*
* -----------------
*
* Shared aggregate (my @a : shared; my %h : shared):
*
* SV = PVAV(0x7175d0) at 0x738708
* FLAGS = (PADMY,RMG)
* MAGIC = 0x824e48
* MG_TYPE = PERL_MAGIC_tied(P)
* MG_OBJ = 0x7136e0 <<<< ref to the tied object
* SV = RV(0x7136f0) at 0x7136e0
* RV = 0x738640
* SV = PVMG(0x7ba238) at 0x738640 <<<< the tied object
* FLAGS = (OBJECT,IOK,pIOK)
* IV = 8455000 <<<< pointer to the shared AV
* STASH = 0x80abf0 "threads::shared::tie"
* MG_PTR = 0x810358 "" <<<< another pointer to the shared AV
* ARRAY = 0x0
*
* -----------------
*
* Aggregate element (my @a : shared; $a[0])
*
* SV = PVLV(0x77f628) at 0x713550
* FLAGS = (GMG,SMG,RMG,pIOK)
* MAGIC = 0x72bd58
* MG_TYPE = PERL_MAGIC_shared_scalar(n)
* MG_PTR = 0x8103c0 "" <<<< pointer to the shared element
* MAGIC = 0x72bd18
* MG_TYPE = PERL_MAGIC_tiedelem(p)
* MG_OBJ = 0x7136e0 <<<< ref to the tied object
* SV = RV(0x7136f0) at 0x7136e0
* RV = 0x738660
* SV = PVMG(0x7ba278) at 0x738660 <<<< the tied object
* FLAGS = (OBJECT,IOK,pIOK)
* IV = 8455064 <<<< pointer to the shared AV
* STASH = 0x80ac30 "threads::shared::tie"
* TYPE = t
*
* Note that PERL_MAGIC_tiedelem(p) magic doesn't have a pointer to a
* shared SV in mg_ptr; instead this is used to store the hash key,
* if any, like normal tied elements. Note also that element SVs may have
* pointers to both the shared aggregate and the shared element.
*
*
* Userland locks:
*
* If a shared variable is used as a perl-level lock or condition
* variable, then PERL_MAGIC_ext magic is attached to the associated
* *shared* SV, whose mg_ptr field points to a malloc'ed structure
* containing the necessary mutexes and condition variables.
*
* Nomenclature:
*
* In this file, any variable name prefixed with 's' (e.g., ssv, stmp or sobj)
* usually represents a shared SV which corresponds to a private SV named
* without the prefix (e.g., sv, tmp or obj).
*/
/* this is lower overhead than warn() and less likely to interfere
with other parts of perl (like with the debugger.)
*/
#ifdef SHARED_TRACE_LOCKS
# define TRACE_LOCK(x) DEBUG_U(x)
# define TRACE_LOCKv(x) DEBUG_Uv(x)
#else
# define TRACE_LOCK(x)
# define TRACE_LOCKv(x)
#endif
#define PERL_NO_GET_CONTEXT
#include "EXTERN.h"
#include "perl.h"
#include "XSUB.h"
#define NEED_sv_2pv_flags
#define NEED_vnewSVpvf
#define NEED_warner
#define NEED_newSVpvn_flags
#include "ppport.h"
#ifndef CLANG_DIAG_IGNORE
# define CLANG_DIAG_IGNORE(x)
# define CLANG_DIAG_RESTORE
#endif
#ifndef CLANG_DIAG_IGNORE_STMT
# define CLANG_DIAG_IGNORE_STMT(x) CLANG_DIAG_IGNORE(x) NOOP
# define CLANG_DIAG_RESTORE_STMT CLANG_DIAG_RESTORE NOOP
#endif
#ifdef USE_ITHREADS
/* Magic signature(s) for mg_private to make PERL_MAGIC_ext magic safer */
#define UL_MAGIC_SIG 0x554C /* UL = user lock */
/*
* The shared things need an interpreter to live in ...
*/
static PerlInterpreter *PL_sharedsv_space; /* The shared sv space */
/* To access shared space we fake aTHX in this scope and thread's context */
/* Bug #24255: We include ENTER+SAVETMPS/FREETMPS+LEAVE with
* SHARED_CONTEXT/CALLER_CONTEXT macros, so that any mortals, etc. created
* while in the shared interpreter context don't languish */
#define SHARED_CONTEXT \
STMT_START { \
PERL_SET_CONTEXT((aTHX = PL_sharedsv_space)); \
ENTER; \
SAVETMPS; \
} STMT_END
/* So we need a way to switch back to the caller's context... */
/* So we declare _another_ copy of the aTHX variable ... */
#define dTHXc PerlInterpreter *caller_perl = aTHX
/* ... and use it to switch back */
#define CALLER_CONTEXT \
STMT_START { \
FREETMPS; \
LEAVE; \
PERL_SET_CONTEXT((aTHX = caller_perl)); \
} STMT_END
/*
* Only one thread at a time is allowed to mess with shared space.
*/
typedef struct {
perl_mutex mutex;
PerlInterpreter *owner;
I32 locks;
perl_cond cond;
#ifdef DEBUG_LOCKS
const char * file;
int line;
#endif
} recursive_lock_t;
static recursive_lock_t PL_sharedsv_lock; /* Mutex protecting the shared sv space */
static void
recursive_lock_init(pTHX_ recursive_lock_t *lock)
{
Zero(lock,1,recursive_lock_t);
MUTEX_INIT(&lock->mutex);
COND_INIT(&lock->cond);
}
static void
recursive_lock_destroy(pTHX_ recursive_lock_t *lock)
{
MUTEX_DESTROY(&lock->mutex);
COND_DESTROY(&lock->cond);
}
static void
recursive_lock_release(pTHX_ recursive_lock_t *lock)
{
MUTEX_LOCK(&lock->mutex);
if (lock->owner == aTHX) {
if (--lock->locks == 0) {
lock->owner = NULL;
COND_SIGNAL(&lock->cond);
TRACE_LOCK(
PerlIO_printf(Perl_debug_log, "shared lock released %p for %p at %s:%d\n",
lock, aTHX, CopFILE(PL_curcop), CopLINE(PL_curcop))
);
}
else {
TRACE_LOCKv(
PerlIO_printf(Perl_debug_log, "shared lock unbump %p for %p at %s:%d\n",
lock, aTHX, CopFILE(PL_curcop), CopLINE(PL_curcop))
);
}
}
else {
TRACE_LOCK(
PerlIO_printf(Perl_debug_log, "bad shared lock release %p for %p (owned by %p) at %s:%d\n",
lock, aTHX, lock->owner, CopFILE(PL_curcop), CopLINE(PL_curcop))
);
}
MUTEX_UNLOCK(&lock->mutex);
}
static void
recursive_lock_acquire(pTHX_ recursive_lock_t *lock, const char *file, int line)
{
PERL_UNUSED_ARG(file);
PERL_UNUSED_ARG(line);
assert(aTHX);
MUTEX_LOCK(&lock->mutex);
if (lock->owner == aTHX) {
TRACE_LOCKv(
PerlIO_printf(Perl_debug_log, "shared lock bump %p (%p) at %s:%d\n",
lock, lock->owner, CopFILE(PL_curcop), CopLINE(PL_curcop))
);
lock->locks++;
} else {
TRACE_LOCK(
PerlIO_printf(Perl_debug_log, "shared lock try %p for %p (owned by %p) at %s:%d\n",
lock, aTHX, lock->owner, CopFILE(PL_curcop), CopLINE(PL_curcop))
);
while (lock->owner) {
#ifdef DEBUG_LOCKS
Perl_warn(aTHX_ " %p waiting - owned by %p %s:%d\n",
aTHX, lock->owner, lock->file, lock->line);
#endif
COND_WAIT(&lock->cond,&lock->mutex);
}
TRACE_LOCK(
PerlIO_printf(Perl_debug_log, "shared lock got %p at %s:%d\n",
lock, CopFILE(PL_curcop), CopLINE(PL_curcop))
);
lock->locks = 1;
lock->owner = aTHX;
#ifdef DEBUG_LOCKS
lock->file = file;
lock->line = line;
#endif
}
MUTEX_UNLOCK(&lock->mutex);
SAVEDESTRUCTOR_X(recursive_lock_release,lock);
}
#define ENTER_LOCK \
STMT_START { \
ENTER; \
recursive_lock_acquire(aTHX_ &PL_sharedsv_lock, __FILE__, __LINE__);\
} STMT_END
/* The unlocking is done automatically at scope exit */
#define LEAVE_LOCK LEAVE
/* A common idiom is to acquire access and switch in ... */
#define SHARED_EDIT \
STMT_START { \
ENTER_LOCK; \
SHARED_CONTEXT; \
} STMT_END
/* ... then switch out and release access. */
#define SHARED_RELEASE \
STMT_START { \
CALLER_CONTEXT; \
LEAVE_LOCK; \
} STMT_END
/* User-level locks:
This structure is attached (using ext magic) to any shared SV that
is used by user-level locking or condition code
*/
typedef struct {
recursive_lock_t lock; /* For user-levl locks */
perl_cond user_cond; /* For user-level conditions */
} user_lock;
/* Magic used for attaching user_lock structs to shared SVs
The vtable used has just one entry - when the SV goes away
we free the memory for the above.
*/
static int
sharedsv_userlock_free(pTHX_ SV *sv, MAGIC *mg)
{
user_lock *ul = (user_lock *) mg->mg_ptr;
PERL_UNUSED_ARG(sv);
assert(aTHX == PL_sharedsv_space);
if (ul) {
recursive_lock_destroy(aTHX_ &ul->lock);
COND_DESTROY(&ul->user_cond);
PerlMemShared_free(ul);
mg->mg_ptr = NULL;
}
return (0);
}
static const MGVTBL sharedsv_userlock_vtbl = {
0, /* get */
0, /* set */
0, /* len */
0, /* clear */
sharedsv_userlock_free, /* free */
0, /* copy */
0, /* dup */
#ifdef MGf_LOCAL
0, /* local */
#endif
};
/* Support for dual-valued variables */
#ifdef SVf_IVisUV
# define DUALVAR_FLAGS(sv) \
((SvPOK(sv)) \
? ((SvNOK(sv) || SvNOKp(sv)) ? SVf_NOK \
: ((SvIsUV(sv)) ? (SVf_IOK | SVf_IVisUV) \
: ((SvIOK(sv) || SvIOKp(sv)) ? SVf_IOK : 0))) \
: 0)
#else
# define DUALVAR_FLAGS(sv) \
((SvPOK(sv)) \
? ((SvNOK(sv) || SvNOKp(sv)) ? SVf_NOK \
: ((SvIOK(sv) || SvIOKp(sv)) ? SVf_IOK : 0)) \
: 0)
#endif
/*
* Access to shared things is heavily based on MAGIC
* - in mg.h/mg.c/sv.c sense
*/
/* In any thread that has access to a shared thing there is a "proxy"
for it in its own space which has 'MAGIC' associated which accesses
the shared thing.
*/
extern const MGVTBL sharedsv_scalar_vtbl; /* Scalars have this vtable */
extern const MGVTBL sharedsv_array_vtbl; /* Hashes and arrays have this
- like 'tie' */
extern const MGVTBL sharedsv_elem_vtbl; /* Elements of hashes and arrays have
this _AS WELL AS_ the scalar magic:
The sharedsv_elem_vtbl associates the element with the array/hash and
the sharedsv_scalar_vtbl associates it with the value
*/
/* Get shared aggregate SV pointed to by threads::shared::tie magic object */
#define SHAREDSV_FROM_OBJ(sv) ((SvROK(sv)) ? INT2PTR(SV *, SvIV(SvRV(sv))) : NULL)
/* Return the user_lock structure (if any) associated with a shared SV.
* If create is true, create one if it doesn't exist
*/
STATIC user_lock *
S_get_userlock(pTHX_ SV* ssv, bool create)
{
MAGIC *mg;
user_lock *ul = NULL;
assert(ssv);
/* XXX Redesign the storage of user locks so we don't need a global
* lock to access them ???? DAPM */
ENTER_LOCK;
/* Version of mg_find that also checks the private signature */
for (mg = SvMAGIC(ssv); mg; mg = mg->mg_moremagic) {
if ((mg->mg_type == PERL_MAGIC_ext) &&
(mg->mg_private == UL_MAGIC_SIG))
{
break;
}
}
if (mg) {
ul = (user_lock*)(mg->mg_ptr);
} else if (create) {
dTHXc;
SHARED_CONTEXT;
ul = (user_lock *) PerlMemShared_malloc(sizeof(user_lock));
Zero(ul, 1, user_lock);
/* Attach to shared SV using ext magic */
mg = sv_magicext(ssv, NULL, PERL_MAGIC_ext, &sharedsv_userlock_vtbl,
(char *)ul, 0);
mg->mg_private = UL_MAGIC_SIG; /* Set private signature */
recursive_lock_init(aTHX_ &ul->lock);
COND_INIT(&ul->user_cond);
CALLER_CONTEXT;
}
LEAVE_LOCK;
return (ul);
}
/* Given a private side SV tries to find if the SV has a shared backend,
* by looking for the magic.
*/
static SV *
Perl_sharedsv_find(pTHX_ SV *sv)
{
MAGIC *mg;
if (SvTYPE(sv) >= SVt_PVMG) {
switch(SvTYPE(sv)) {
case SVt_PVAV:
case SVt_PVHV:
if ((mg = mg_find(sv, PERL_MAGIC_tied))
&& mg->mg_virtual == &sharedsv_array_vtbl) {
return ((SV *)mg->mg_ptr);
}
break;
default:
/* This should work for elements as well as they
* have scalar magic as well as their element magic
*/
if ((mg = mg_find(sv, PERL_MAGIC_shared_scalar))
&& mg->mg_virtual == &sharedsv_scalar_vtbl) {
return ((SV *)mg->mg_ptr);
}
break;
}
}
/* Just for tidyness of API also handle tie objects */
if (SvROK(sv) && sv_derived_from(sv, "threads::shared::tie")) {
return (SHAREDSV_FROM_OBJ(sv));
}
return (NULL);
}
/* Associate a private SV with a shared SV by pointing the appropriate
* magics at it.
* Assumes lock is held.
*/
static void
Perl_sharedsv_associate(pTHX_ SV *sv, SV *ssv)
{
MAGIC *mg = 0;
/* If we are asked for any private ops we need a thread */
assert ( aTHX != PL_sharedsv_space );
/* To avoid need for recursive locks require caller to hold lock */
assert ( PL_sharedsv_lock.owner == aTHX );
switch(SvTYPE(sv)) {
case SVt_PVAV:
case SVt_PVHV:
if (!(mg = mg_find(sv, PERL_MAGIC_tied))
|| mg->mg_virtual != &sharedsv_array_vtbl
|| (SV*) mg->mg_ptr != ssv)
{
SV *obj = newSV(0);
sv_setref_iv(obj, "threads::shared::tie", PTR2IV(ssv));
if (mg) {
sv_unmagic(sv, PERL_MAGIC_tied);
}
mg = sv_magicext(sv, obj, PERL_MAGIC_tied, &sharedsv_array_vtbl,
(char *)ssv, 0);
mg->mg_flags |= (MGf_COPY|MGf_DUP);
SvREFCNT_inc_void(ssv);
SvREFCNT_dec(obj);
}
break;
default:
if ((SvTYPE(sv) < SVt_PVMG)
|| !(mg = mg_find(sv, PERL_MAGIC_shared_scalar))
|| mg->mg_virtual != &sharedsv_scalar_vtbl
|| (SV*) mg->mg_ptr != ssv)
{
if (mg) {
sv_unmagic(sv, PERL_MAGIC_shared_scalar);
}
mg = sv_magicext(sv, Nullsv, PERL_MAGIC_shared_scalar,
&sharedsv_scalar_vtbl, (char *)ssv, 0);
mg->mg_flags |= (MGf_DUP
#ifdef MGf_LOCAL
|MGf_LOCAL
#endif
);
SvREFCNT_inc_void(ssv);
}
break;
}
assert ( Perl_sharedsv_find(aTHX_ sv) == ssv );
}
/* Given a private SV, create and return an associated shared SV.
* Assumes lock is held.
*/
STATIC SV *
S_sharedsv_new_shared(pTHX_ SV *sv)
{
dTHXc;
SV *ssv;
assert(PL_sharedsv_lock.owner == aTHX);
assert(aTHX != PL_sharedsv_space);
SHARED_CONTEXT;
ssv = newSV(0);
SvREFCNT(ssv) = 0; /* Will be upped to 1 by Perl_sharedsv_associate */
sv_upgrade(ssv, SvTYPE(sv));
CALLER_CONTEXT;
Perl_sharedsv_associate(aTHX_ sv, ssv);
return (ssv);
}
/* Given a shared SV, create and return an associated private SV.
* Assumes lock is held.
*/
STATIC SV *
S_sharedsv_new_private(pTHX_ SV *ssv)
{
SV *sv;
assert(PL_sharedsv_lock.owner == aTHX);
assert(aTHX != PL_sharedsv_space);
sv = newSV(0);
sv_upgrade(sv, SvTYPE(ssv));
Perl_sharedsv_associate(aTHX_ sv, ssv);
return (sv);
}
/* A threadsafe version of SvREFCNT_dec(ssv) */
STATIC void
S_sharedsv_dec(pTHX_ SV* ssv)
{
if (! ssv)
return;
ENTER_LOCK;
if (SvREFCNT(ssv) > 1) {
/* No side effects, so can do it lightweight */
SvREFCNT_dec(ssv);
} else {
dTHXc;
SHARED_CONTEXT;
SvREFCNT_dec(ssv);
CALLER_CONTEXT;
}
LEAVE_LOCK;
}
/* Implements Perl-level share() and :shared */
static void
Perl_sharedsv_share(pTHX_ SV *sv)
{
switch(SvTYPE(sv)) {
case SVt_PVGV:
Perl_croak(aTHX_ "Cannot share globs yet");
break;
case SVt_PVCV:
Perl_croak(aTHX_ "Cannot share subs yet");
break;
default:
ENTER_LOCK;
(void) S_sharedsv_new_shared(aTHX_ sv);
LEAVE_LOCK;
SvSETMAGIC(sv);
break;
}
}
#ifdef WIN32
/* Number of milliseconds from 1/1/1601 to 1/1/1970 */
#define EPOCH_BIAS 11644473600000.
/* Returns relative time in milliseconds. (Adapted from Time::HiRes.) */
STATIC DWORD
S_abs_2_rel_milli(double abs)
{
double rel;
/* Get current time (in units of 100 nanoseconds since 1/1/1601) */
union {
FILETIME ft;
__int64 i64; /* 'signed' to keep compilers happy */
} now;
GetSystemTimeAsFileTime(&now.ft);
/* Relative time in milliseconds */
rel = (abs * 1000.) - (((double)now.i64 / 10000.) - EPOCH_BIAS);
if (rel <= 0.0) {
return (0);
}
return (DWORD)rel;
}
#else
# if defined(OS2)
# define ABS2RELMILLI(abs) \
do { \
abs -= (double)time(NULL); \
if (abs > 0) { abs *= 1000; } \
else { abs = 0; } \
} while (0)
# endif /* OS2 */
#endif /* WIN32 */
/* Do OS-specific condition timed wait */
static bool
Perl_sharedsv_cond_timedwait(perl_cond *cond, perl_mutex *mut, double abs)
{
#if defined(NETWARE) || defined(I_MACH_CTHREADS)
Perl_croak_nocontext("cond_timedwait not supported on this platform");
#else
# ifdef WIN32
int got_it = 0;
cond->waiters++;
MUTEX_UNLOCK(mut);
/* See comments in win32/win32thread.h COND_WAIT vis-a-vis race */
switch (WaitForSingleObject(cond->sem, S_abs_2_rel_milli(abs))) {
case WAIT_OBJECT_0: got_it = 1; break;
case WAIT_TIMEOUT: break;
default:
/* WAIT_FAILED? WAIT_ABANDONED? others? */
Perl_croak_nocontext("panic: cond_timedwait (%ld)",GetLastError());
break;
}
MUTEX_LOCK(mut);
cond->waiters--;
return (got_it);
# else
# ifdef OS2
int rc, got_it = 0;
STRLEN n_a;
ABS2RELMILLI(abs);
if ((rc = DosResetEventSem(*cond,&n_a)) && (rc != ERROR_ALREADY_RESET))
Perl_rc = rc, croak_with_os2error("panic: cond_timedwait-reset");
MUTEX_UNLOCK(mut);
if (CheckOSError(DosWaitEventSem(*cond,abs))
&& (rc != ERROR_INTERRUPT))
croak_with_os2error("panic: cond_timedwait");
if (rc == ERROR_INTERRUPT) errno = EINTR;
MUTEX_LOCK(mut);
return (got_it);
# else /* Hope you're I_PTHREAD! */
struct timespec ts;
int got_it = 0;
ts.tv_sec = (long)abs;
abs -= (NV)ts.tv_sec;
ts.tv_nsec = (long)(abs * 1000000000.0);
CLANG_DIAG_IGNORE_STMT(-Wthread-safety);
/* warning: calling function 'pthread_cond_timedwait' requires holding mutex 'mut' exclusively [-Wthread-safety-analysis] */
switch (pthread_cond_timedwait(cond, mut, &ts)) {
CLANG_DIAG_RESTORE_STMT;
case 0: got_it = 1; break;
case ETIMEDOUT: break;
#ifdef OEMVS
case -1:
if (errno == ETIMEDOUT || errno == EAGAIN)
break;
#endif
default:
Perl_croak_nocontext("panic: cond_timedwait");
break;
}
return (got_it);
# endif /* OS2 */
# endif /* WIN32 */
#endif /* NETWARE || I_MACH_CTHREADS */
}
/* Given a thingy referenced by a shared RV, copy it's value to a private
* RV, also copying the object status of the referent.
* If the private side is already an appropriate RV->SV combination, keep
* it if possible.
*/
STATIC void
S_get_RV(pTHX_ SV *sv, SV *sobj) {
SV *obj;
if (! (SvROK(sv) &&
((obj = SvRV(sv))) &&
(Perl_sharedsv_find(aTHX_ obj) == sobj) &&
(SvTYPE(obj) == SvTYPE(sobj))))
{
/* Can't reuse obj */
if (SvROK(sv)) {
SvREFCNT_dec(SvRV(sv));
} else {
assert(SvTYPE(sv) >= SVt_RV);
sv_setsv_nomg(sv, &PL_sv_undef);
SvROK_on(sv);
}
obj = S_sharedsv_new_private(aTHX_ sobj);
SvRV_set(sv, obj);
}
if (SvOBJECT(obj)) {
/* Remove any old blessing */
SvREFCNT_dec(SvSTASH(obj));
SvOBJECT_off(obj);
}
if (SvOBJECT(sobj)) {
/* Add any new old blessing */
STRLEN len;
char* stash_ptr = SvPV((SV*) SvSTASH(sobj), len);
HV* stash = gv_stashpvn(stash_ptr, len, TRUE);
SvOBJECT_on(obj);
SvSTASH_set(obj, (HV*)SvREFCNT_inc(stash));
}
}
/* Every caller of S_get_RV needs this incantation (which cannot go inside
S_get_RV itself, as we do not want recursion beyond one level): */
#define get_RV(sv, sobj) \
S_get_RV(aTHX_ sv, sobj); \
/* Look ahead for refs of refs */ \
if (SvROK(sobj)) { \
SvROK_on(SvRV(sv)); \
S_get_RV(aTHX_ SvRV(sv), SvRV(sobj)); \
}
/* ------------ PERL_MAGIC_shared_scalar(n) functions -------------- */
/* Get magic for PERL_MAGIC_shared_scalar(n) */
static int
sharedsv_scalar_mg_get(pTHX_ SV *sv, MAGIC *mg)
{
SV *ssv = (SV *) mg->mg_ptr;
assert(ssv);
ENTER_LOCK;
if (SvROK(ssv)) {
get_RV(sv, SvRV(ssv));
} else {
sv_setsv_nomg(sv, ssv);
}
LEAVE_LOCK;
return (0);
}
/* Copy the contents of a private SV to a shared SV.
* Used by various mg_set()-type functions.
* Assumes lock is held.
*/
static void
sharedsv_scalar_store(pTHX_ SV *sv, SV *ssv)
{
dTHXc;
bool allowed = TRUE;
assert(PL_sharedsv_lock.owner == aTHX);
if (!PL_dirty && SvROK(ssv) && SvREFCNT(SvRV(ssv)) == 1) {
SV *sv = sv_newmortal();
sv_upgrade(sv, SVt_RV);
get_RV(sv, SvRV(ssv));
}
if (SvROK(sv)) {
SV *obj = SvRV(sv);
SV *sobj = Perl_sharedsv_find(aTHX_ obj);
if (sobj) {
SV* tmpref;
SHARED_CONTEXT;
/* Creating a tmp ref to sobj then assigning it to ssv ensures
* that any previous contents of ssv are correctly freed
* by sv_setsv(). Not sure if there is a better, API-legal way
* to achieve this */
tmpref = newRV_inc(sobj);
sv_setsv_nomg(ssv, tmpref);
SvREFCNT_dec_NN(tmpref);
if (SvOBJECT(sobj)) {
/* Remove any old blessing */
SvREFCNT_dec(SvSTASH(sobj));
SvOBJECT_off(sobj);
}
if (SvOBJECT(obj)) {
SV* fake_stash = newSVpv(HvNAME_get(SvSTASH(obj)),0);
SvOBJECT_on(sobj);
SvSTASH_set(sobj, (HV*)fake_stash);
}
CALLER_CONTEXT;
} else {
allowed = FALSE;
}
} else {
SvTEMP_off(sv);
SHARED_CONTEXT;
sv_setsv_nomg(ssv, sv);
if (SvOBJECT(ssv)) {
/* Remove any old blessing */
SvREFCNT_dec(SvSTASH(ssv));
SvOBJECT_off(ssv);
}
if (SvOBJECT(sv)) {
SV* fake_stash = newSVpv(HvNAME_get(SvSTASH(sv)),0);
SvOBJECT_on(ssv);
SvSTASH_set(ssv, (HV*)fake_stash);
}
CALLER_CONTEXT;
}
if (!allowed) {
Perl_croak(aTHX_ "Invalid value for shared scalar");
}
}
/* Set magic for PERL_MAGIC_shared_scalar(n) */
static int
sharedsv_scalar_mg_set(pTHX_ SV *sv, MAGIC *mg)
{
SV *ssv = (SV*)(mg->mg_ptr);
assert(ssv);
ENTER_LOCK;
if (SvTYPE(ssv) < SvTYPE(sv)) {
dTHXc;
SHARED_CONTEXT;
sv_upgrade(ssv, SvTYPE(sv));
CALLER_CONTEXT;
}
sharedsv_scalar_store(aTHX_ sv, ssv);
LEAVE_LOCK;
return (0);
}
/* Free magic for PERL_MAGIC_shared_scalar(n) */
static int
sharedsv_scalar_mg_free(pTHX_ SV *sv, MAGIC *mg)
{
PERL_UNUSED_ARG(sv);
ENTER_LOCK;
if (!PL_dirty
&& SvROK((SV *)mg->mg_ptr) && SvREFCNT(SvRV((SV *)mg->mg_ptr)) == 1) {
SV *sv = sv_newmortal();
sv_upgrade(sv, SVt_RV);
get_RV(sv, SvRV((SV *)mg->mg_ptr));
}
S_sharedsv_dec(aTHX_ (SV*)mg->mg_ptr);
LEAVE_LOCK;
return (0);
}
/*
* Called during cloning of PERL_MAGIC_shared_scalar(n) magic in new thread
*/
static int
sharedsv_scalar_mg_dup(pTHX_ MAGIC *mg, CLONE_PARAMS *param)
{
PERL_UNUSED_ARG(param);
SvREFCNT_inc_void(mg->mg_ptr);
return (0);
}
#ifdef MGf_LOCAL
/*
* Called during local $shared
*/
static int
sharedsv_scalar_mg_local(pTHX_ SV* nsv, MAGIC *mg)
{
MAGIC *nmg;
SV *ssv = (SV *) mg->mg_ptr;
if (ssv) {
ENTER_LOCK;
SvREFCNT_inc_void(ssv);
LEAVE_LOCK;
}
nmg = sv_magicext(nsv, mg->mg_obj, mg->mg_type, mg->mg_virtual,
mg->mg_ptr, mg->mg_len);
nmg->mg_flags = mg->mg_flags;
nmg->mg_private = mg->mg_private;
return (0);
}
#endif
const MGVTBL sharedsv_scalar_vtbl = {
sharedsv_scalar_mg_get, /* get */
sharedsv_scalar_mg_set, /* set */
0, /* len */
0, /* clear */
sharedsv_scalar_mg_free, /* free */
0, /* copy */
sharedsv_scalar_mg_dup, /* dup */
#ifdef MGf_LOCAL
sharedsv_scalar_mg_local, /* local */
#endif
};
/* ------------ PERL_MAGIC_tiedelem(p) functions -------------- */
/* Get magic for PERL_MAGIC_tiedelem(p) */
static int
sharedsv_elem_mg_FETCH(pTHX_ SV *sv, MAGIC *mg)
{
dTHXc;
SV *saggregate = SHAREDSV_FROM_OBJ(mg->mg_obj);
SV** svp = NULL;
ENTER_LOCK;
if (saggregate) { /* During global destruction, underlying
aggregate may no longer exist */
if (SvTYPE(saggregate) == SVt_PVAV) {
assert ( mg->mg_ptr == 0 );
SHARED_CONTEXT;
svp = av_fetch((AV*) saggregate, mg->mg_len, 0);
} else {
char *key = mg->mg_ptr;
I32 len = mg->mg_len;
assert ( mg->mg_ptr != 0 );
if (mg->mg_len == HEf_SVKEY) {
STRLEN slen;
key = SvPV((SV *)mg->mg_ptr, slen);
len = slen;
if (SvUTF8((SV *)mg->mg_ptr)) {
len = -len;
}
}
SHARED_CONTEXT;
svp = hv_fetch((HV*) saggregate, key, len, 0);
}
CALLER_CONTEXT;
}
if (svp) {
/* Exists in the array */
if (SvROK(*svp)) {
get_RV(sv, SvRV(*svp));
} else {
/* $ary->[elem] or $ary->{elem} is a scalar */
Perl_sharedsv_associate(aTHX_ sv, *svp);
sv_setsv(sv, *svp);
}
} else {
/* Not in the array */
sv_setsv(sv, &PL_sv_undef);
}
LEAVE_LOCK;
return (0);
}
/* Set magic for PERL_MAGIC_tiedelem(p) */